JP6111271B2 - Mobile communication system, communication control method, base station, user terminal, and processor - Google Patents

Description

  The present invention relates to a mobile communication system, a communication control method, a base station, a user terminal, and a processor that support CoMP.

  In 3GPP (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, standardization of CoMP (Coordinated Multi-Point) is scheduled to proceed after Release 11 (see Non-Patent Document 1). CoMP is a communication mode in which transmission / reception points (base stations or cells) in the same place are positioned as one “point”, and a plurality of points cooperate to communicate with a user terminal.

  As downlink CoMP schemes, JT (Joint Transmission), DPS (Dynamic Point Selection), CS (Coordinated Scheduling), and CB (Coordinated Beamforming) have been proposed.

  JT-CoMP is a method in which a plurality of points simultaneously transmit to user terminals using the same radio resource. DPS-CoMP and CS-CoMP are systems in which a plurality of points secure the same radio resource and selectively transmit to a user terminal. CB-CoMP is a method in which a plurality of points perform beamforming / null steering of a transmission beam in a coordinated manner.

3GPP Technical Report “TR 36.819 V11.1.0” December 2011

  However, the above-described CoMP methods have the following problems.

  Since JT-CoMP, DPS-CoMP, and CS-CoMP consume radio resources at each point for one user terminal, there is a problem that the utilization efficiency of radio resources decreases.

  Although CB-CoMP can suppress a decrease in utilization efficiency of radio resources, each point needs to have a plurality of antennas, and there is a problem that the cost (equipment cost and installation cost) of each point is high.

  Therefore, the present invention provides a mobile communication system, a communication control method, a base station, a user terminal, and a processor that realize a new CoMP scheme that can solve the above-described problems.

  A mobile communication system according to an embodiment receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal, and a first base station that manages the serving cell And having. The first base station generates an interference replica signal corresponding to the interference wave signal, superimposes the interference replica signal on the desired wave signal, and the desired wave signal on which the interference replica signal is superimposed. And a transmission unit for transmitting to the user terminal. The control unit generates the interference replica signal so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal.

It is a block diagram of the LTE system which concerns on 1st Embodiment and 2nd Embodiment. It is a block diagram of UE which concerns on 1st Embodiment and 2nd Embodiment. It is a block diagram of eNB which concerns on 1st Embodiment and 2nd Embodiment. It is a protocol stack figure of the radio | wireless interface in a LTE system. It is a block diagram of the radio | wireless frame used with a LTE system. It is a block diagram of the radio | wireless frame used by a downlink. It is a figure for demonstrating the outline | summary of the cooperative interference cancellation system which concerns on 1st Embodiment and 2nd Embodiment. It is a block diagram of eNB for implement | achieving the cooperative interference cancellation system which concerns on 1st Embodiment and 2nd Embodiment. It is a sequence diagram of the operation | movement pattern 1 which concerns on 1st Embodiment. It is a sequence diagram of the operation example 1 for acquiring the channel information 2 which concerns on 1st Embodiment. It is a sequence diagram of the operation example 2 for acquiring the channel information 2 which concerns on 1st Embodiment. It is a sequence diagram of the operation example 3 for acquiring the channel information 2 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 2 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 3 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 4 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 5 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 6 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 7 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 8 which concerns on 1st Embodiment. It is a sequence diagram of the operation | movement pattern 1 which concerns on 2nd Embodiment. It is a sequence diagram of the operation | movement pattern 2 which concerns on 2nd Embodiment. It is a sequence diagram of the operation | movement pattern 3 which concerns on 2nd Embodiment. It is a sequence diagram of the operation | movement pattern 4 which concerns on 2nd Embodiment. It is a sequence diagram of the operation | movement pattern 5 which concerns on 2nd Embodiment.

[Outline of Embodiment]
A mobile communication system according to an embodiment receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal, and a first base station that manages the serving cell; Have. The first base station generates an interference replica signal corresponding to the interference wave signal, superimposes the interference replica signal on the desired wave signal, and the desired wave signal on which the interference replica signal is superimposed. And a transmission unit for transmitting to the user terminal. The control unit generates the interference replica signal so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal.

  According to such a method, since the reception power of the interference wave signal in the user terminal can be reduced, the desired wave-to-interference ratio (SIR) can be improved. Furthermore, even when the base station does not have a plurality of antennas, that is, when beam forming / null steering is not possible, this method can be applied.

  In the embodiment, the other user terminal is connected to an adjacent cell adjacent to the serving cell, and the interference wave signal is a signal from the adjacent cell. Thereby, since it is not necessary to secure a radio | wireless resource for the said user terminal in an adjacent cell, the utilization efficiency of a radio | wireless resource can be improved compared with JT-CoMP, DPS-CoMP, and CS-CoMP.

  In the embodiment, the first base station manages the serving cell connected to the user terminal and an adjacent cell adjacent to the serving cell connected to the other user terminal, and the transmission unit transmits the interference wave signal. Transmit to the other user terminal.

  In the embodiment, the other user terminal is located in the serving cell to which the user terminal is connected, and the transmission unit transmits the interference wave signal to the other user terminal.

  In the embodiment, the first base station manages communication with the user terminal and communication with the other user terminal, and the transmission unit transmits the interference wave signal to the other user terminal. Send to.

  In the embodiment, the control unit generates the interference replica signal so that the phase of the interference replica signal received by the user terminal is opposite to the phase of the interference wave signal received by the user terminal.

  In the embodiment, the control unit generates the interference replica signal so that the amplitude of the interference replica signal received by the user terminal is the same as the amplitude of the interference wave signal received by the user terminal.

  In an embodiment, the first base station includes at least one antenna associated with the serving cell. The control unit determines whether to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on the number of antennas.

  In the embodiment, the control unit determines whether or not to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on a reception signal state in the user terminal.

  In the embodiment, the control unit determines whether or not to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on a usage state of radio resources in the mobile communication system.

  In the embodiment, the control unit determines whether or not to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on QoS required by the user terminal.

  In the embodiment, the mobile communication system further includes a management device that manages the first base station. The first base station includes a reception unit that receives information used to generate the interference replica signal from at least one of the management device and the user terminal. The control unit generates the interference replica signal based on information received by the receiving unit.

  In the embodiment, the mobile communication system further includes a second base station that manages the neighboring cell, the management device manages the second base station, and the reception unit includes the interference replica signal. The information used for generating is received from at least one of the second base station, the management device, and the user terminal.

  In the embodiment, the information used for generating the interference replica signal includes waveform information related to a signal waveform of the interference wave signal. The second base station transmits the waveform information to the first base station. The receiving unit receives the waveform information.

  In the embodiment, the control unit transmits resource information indicating a radio resource used for transmitting the desired signal to the second base station. The second base station transmits the waveform information to the first base station based on the resource information.

  In the embodiment, the information used for generating the interference replica signal includes transmission data before being converted into the interference wave signal in the second base station. The second base station transmits the transmission data to the first base station. The receiving unit receives the transmission data from the second base station.

  In the embodiment, the information used for generating the interference replica signal further includes transmission processing information indicating a content of transmission processing when the transmission data is converted into the interference wave signal in the second base station. The second base station further transmits the transmission processing information to the first base station. The receiving unit further receives the transmission processing information from the second base station.

  In the embodiment, the information used for generating the interference replica signal includes transmission data before being converted into the interference wave signal in the second base station. The management device transmits the transmission data to the first base station. The receiving unit receives the transmission data from the management device.

  In the embodiment, the information used for generating the interference replica signal further includes transmission processing information indicating a content of transmission processing when the transmission data is converted into the interference wave signal in the second base station. The second base station transmits the transmission processing information to the first base station. The receiving unit receives the transmission processing information from the second base station.

  In the embodiment, the interference wave signal includes a data signal transmitted on a physical downlink shared channel. The information used for generating the interference replica signal is difference information indicating at least one of an amplitude difference or a phase difference between the reference signal transmitted by the second base station and the data signal. The second base station transmits the difference information to the first base station. The receiving unit receives the difference information from the second base station.

  In the embodiment, the information used for generating the interference replica signal is reception power information indicating reception power for a reference signal that the user terminal receives from the second base station. The user terminal transmits the received power information to the second base station. The second base station transfers the received power information to the first base station. The receiving unit receives the received power information from the second base station.

  In the embodiment, the information used for generating the interference replica signal is reception power information indicating reception power for a reference signal that the user terminal receives from the second base station. The user terminal transmits the received power information to the first base station. The receiving unit receives the received power information from the user terminal.

  In the embodiment, the interference wave signal includes a data signal transmitted on a physical downlink shared channel. The information used for generating the interference replica signal is power difference information indicating a power difference between the reference signal transmitted by the second base station and the data signal. The user terminal transmits the power difference information to the first base station. The receiving unit receives the power difference information from the user terminal.

  In the embodiment, the interference wave signal includes a data signal transmitted on a physical downlink shared channel. The information used for generating the interference replica signal is power difference information indicating a power difference between the reference signal transmitted by the second base station and the data signal. The second base station transmits the power difference information to the first base station. The receiving unit receives the power difference information from the second base station.

  In the embodiment, the information used for generating the interference replica signal includes a delay time from the first base station to the user terminal and a delay time from the second base station to the user terminal. It is the time difference information which shows the delay time difference between. The user terminal transmits the time difference information to the first base station. The receiving unit receives the time difference information from the user terminal.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the second base station and the user terminal. The receiving unit receives the channel information from at least one of the second base station and the user terminal. The control unit generates the interference replica signal based on the channel information received by the receiving unit.

  In the embodiment, the user terminal generates the channel information based on a reference signal received from the second base station, and transmits the generated channel information to the first base station. The receiving unit receives the channel information from the user terminal.

  In the embodiment, the user terminal generates the channel information based on a reference signal received from the second base station, and transmits the generated channel information to the second base station. The second base station transfers the channel information from the user terminal to the first base station. The receiving unit receives the channel information from the second base station.

  In the embodiment, the first base station transmits cell designation information indicating a cell to be estimated for channel characteristics to the user terminal. The user terminal generates the channel information by estimating channel characteristics for a cell indicated by the cell designation information.

  In the embodiment, the second base station generates the channel information based on a reference signal received from the user terminal, and transmits the generated channel information to the first base station. The receiving unit receives the channel information from the second base station.

  In the embodiment, the first base station transmits terminal designation information indicating a user terminal to be estimated for channel characteristics to the second base station. The second base station generates the channel information by estimating channel characteristics of the user terminal indicated by the terminal designation information.

  In the embodiment, the first base station transmits demodulation information for demodulating the reference signal transmitted by the user terminal to the second base station. The second base station generates the channel information by demodulating the reference signal using the demodulation information.

  A communication control method according to an embodiment includes a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal; a first base station that manages the serving cell; Are used in a mobile communication system. The communication control method includes a generation step of generating an interference replica signal corresponding to the interference wave signal in the first base station, a superposition step of superimposing the interference replica signal on the desired wave signal, and the interference replica. Transmitting the desired wave signal on which the signal is superimposed to the user terminal. In the generation step, the interference replica signal is generated such that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal.

  In the embodiment, the mobile communication system manages a second base station that manages an adjacent cell that is adjacent to the serving cell and is connected to the other user terminal, and the first base station and the second base station. And a management device. The communication control method receives information used to generate the interference replica signal from at least one of the second base station, the management device, and the user terminal in the first base station. Includes a receiving step. In the generation step, the interference replica signal is generated based on the information received in the reception step.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the second base station and the user terminal.

  The base station which concerns on embodiment manages the said serving cell in the mobile communication system which has a user terminal which receives the desired wave signal from a serving cell, and receives the interference wave signal which is a signal with respect to another user terminal. The base station generates an interference replica signal corresponding to the interference wave signal, superimposes the interference replica signal on the desired wave signal, and transmits the desired wave signal on which the interference replica signal is superimposed to the user. And a transmission unit for transmitting to the terminal. The control unit generates the interference replica signal so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal.

  In the embodiment, the base station manages the information used for generating the interference replica signal, the other base station that manages the neighboring cell adjacent to the serving cell and connected to the other user terminal, the base station, and the other It further includes a management unit that manages a base station, and a reception unit that receives from at least one of the user terminals. The control unit generates the interference replica signal based on information received by the receiving unit.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the other base station and the user terminal.

  The base station according to the embodiment manages the adjacent cell in a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal from an adjacent cell adjacent to the serving cell. Another base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal. The base station includes a transmitter that transmits information used to generate the interference replica signal to the other base station.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the base station and the user terminal.

  The user terminal which concerns on embodiment receives the interference wave signal which is a signal to other user terminals while receiving the desired wave signal from a serving cell. The first base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal. The user terminal includes a transmission unit that transmits information used to generate the interference replica signal to the first base station.

  In the embodiment, the information used for generating the interference replica signal is a channel characteristic between the second base station that manages the neighboring cell adjacent to the serving cell and connected to the other user terminal, and the user terminal. Is channel information.

  A processor according to an embodiment receives a desired wave signal from a serving cell and a base station that manages the serving cell in a mobile communication system having a user terminal that receives an interference wave signal that is a signal to another user terminal. Provided. The processor includes a generation process for generating an interference replica signal corresponding to the interference wave signal, a superposition process for superimposing the interference replica signal on the desired wave signal, and the desired wave signal on which the interference replica signal is superimposed. And a transmission process for transmitting to the user terminal. In the generation process, the interference replica signal is generated such that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal.

  In an embodiment, the processor uses the base station, the base station, and the other base that manage information used for generating the interference replica signal to a neighboring cell adjacent to the serving cell and connected to the other user terminal. A reception process for receiving from at least one of the management apparatus that manages the station and the user terminal is further executed. In the generation process, the interference replica signal is generated based on the received information.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the other base station and the user terminal.

  The processor which concerns on embodiment is a base station which manages the said adjacent cell in the mobile communication system which has a user terminal which receives the interference wave signal from the adjacent cell which adjoins the said serving cell while receiving the desired wave signal from a serving cell Prepared for. Another base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal. The processor performs processing for transmitting information used to generate the interference replica signal to the other base station.

  In the embodiment, the information used for generating the interference replica signal is channel information indicating channel characteristics between the base station and the user terminal.

  The processor which concerns on embodiment is equipped with the user terminal which receives the interference wave signal which is a signal to other user terminals while receiving the desired wave signal from a serving cell. The first base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal. The processor performs processing for transmitting information used to generate the interference replica signal to the first base station.

  In the embodiment, the information used for generating the interference replica signal is a channel characteristic between the second base station that manages the neighboring cell adjacent to the serving cell and connected to the other user terminal, and the user terminal. Is channel information.

[First Embodiment]
Hereinafter, an embodiment in which the present invention is applied to a mobile communication system (LTE system) configured in accordance with the 3GPP standard will be described with reference to the drawings.

(LTE system)
FIG. 1 is a configuration diagram of an LTE system according to the present embodiment.

  1, the LTE system includes a plurality of UEs (User Equipment) 100, an E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 10, and an EPC (Evolved Packet Core) 20. The EPC 20 corresponds to a core network.

  The UE 100 is a mobile radio communication device, and performs radio communication with a cell (serving cell) that has established a connection. UE100 is corresponded to a user terminal.

  The E-UTRAN 10 includes a plurality of eNBs 200 (evolved Node-B). The eNB 200 corresponds to a base station. The eNB 200 manages one or a plurality of cells, and performs radio communication with the UE 100 that has established a connection with the own cell.

  Note that “cell” is used as a term indicating a minimum unit of a radio communication area, and is also used as a term indicating a function of performing radio communication with the UE 100.

  The eNB 200 has a radio resource management (RRM) function, a user data routing function, and a measurement control function for mobility control and scheduling.

  The EPC 20 includes a plurality of MME (Mobility Management Entity) / S-GW (Serving-Gateway) 300.

  The MME is a network node that performs various types of mobility control for the UE 100, and corresponds to a control station. The S-GW is a network node that performs transfer control of user data, and corresponds to an exchange. EPC20 comprised by MME / S-GW300 accommodates eNB200.

  The eNB 200 is connected to each other via the X2 interface. Moreover, eNB200 is connected with MME / S-GW300 via S1 interface.

  Next, configurations of the UE 100 and the eNB 200 will be described.

  FIG. 2 is a block diagram of the UE 100. As shown in FIG. 2, the UE 100 includes an antenna 101, a radio transceiver 110, a user interface 120, a GNSS (Global Navigation Satellite System) receiver 130, a battery 140, a memory 150, and a processor 160. Have. The memory 150 and the processor 160 constitute a control unit.

  The UE 100 may not have the GNSS receiver 130. Further, the memory 150 may be integrated with the processor 160, and this set (that is, a chip set) may be used as the processor 160 '.

  The antenna 101 and the wireless transceiver 110 are used for transmitting and receiving wireless signals. A plurality of antennas 101 may be provided. The radio transceiver 110 converts the baseband signal output from the processor 160 into a radio signal and transmits it from the antenna 101. Further, the radio transceiver 110 converts a radio signal received by the antenna 101 into a baseband signal and outputs the baseband signal to the processor 160.

  The user interface 120 is an interface with a user who owns the UE 100, and includes, for example, a display, a microphone, a speaker, and various buttons. The user interface 120 receives an operation from the user and outputs a signal indicating the content of the operation to the processor 160.

  The GNSS receiver 130 receives a GNSS signal and outputs the received signal to the processor 160 in order to obtain location information indicating the geographical location of the UE 100.

  The battery 140 stores power to be supplied to each block of the UE 100.

  The memory 150 stores a program executed by the processor 160 and information used for processing by the processor 160.

  The processor 160 includes a baseband processor that performs modulation / demodulation and encoding / decoding of a baseband signal, and a CPU (Central Processing Unit) that executes programs stored in the memory 150 and performs various processes. . The processor 160 may further include a codec that performs encoding / decoding of an audio / video signal. The processor 160 executes various processes and various communication protocols described later.

  FIG. 3 is a block diagram of the eNB 200. As illustrated in FIG. 3, the eNB 200 includes an antenna 201, a radio transceiver 210, a network interface 220, a memory 230, and a processor 240. The memory 230 and the processor 240 constitute a control unit. The memory 230 may be integrated with the processor 240, and this set (that is, a chip set) may be used as the processor.

  The antenna 201 and the wireless transceiver 210 are used for transmitting and receiving wireless signals. A plurality of antennas 201 may be provided. The wireless transceiver 210 converts the baseband signal output from the processor 240 into a wireless signal and transmits it from the antenna 201. In addition, the radio transceiver 210 converts a radio signal received by the antenna 201 into a baseband signal and outputs the baseband signal to the processor 240.

  The network interface 220 is connected to the neighboring eNB 200 via the X2 interface and is connected to the MME / S-GW 300 via the S1 interface. The network interface 220 is used for communication performed on the X2 interface and communication performed on the S1 interface.

  The memory 230 stores a program executed by the processor 240 and information used for processing by the processor 240.

  The processor 240 includes a baseband processor that performs modulation / demodulation and encoding / decoding of a baseband signal, and a CPU that executes programs stored in the memory 230 and performs various processes. The processor 240 executes various processes and various communication protocols described later.

  FIG. 4 is a protocol stack diagram of a radio interface in the LTE system.

  As shown in FIG. 4, the radio interface protocol is divided into layers 1 to 3 of the OSI reference model, and layer 1 is a physical (PHY) layer. Layer 2 includes a MAC (Media Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer. Layer 3 includes an RRC (Radio Resource Control) layer.

  The physical layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, resource mapping / demapping, and the like. Data is transmitted between the physical layer of the UE 100 and the physical layer of the eNB 200 via a physical channel.

  The MAC layer performs data priority control, retransmission processing by hybrid ARQ (HARQ), and the like. Data is transmitted via the transport channel between the MAC layer of the UE 100 and the MAC layer of the eNB 200. The MAC layer of the eNB 200 includes a scheduler that determines an uplink / downlink transport format (transport block size, modulation / coding scheme, and the like) and an allocated resource block.

  The RLC layer transmits data to the RLC layer on the receiving side using functions of the MAC layer and the physical layer. Data is transmitted between the RLC layer of the UE 100 and the RLC layer of the eNB 200 via a logical channel.

  The PDCP layer performs header compression / decompression and encryption / decryption.

  The RRC layer is defined only in the control plane. Control messages (RRC messages) for various settings are transmitted between the RRC layer of the UE 100 and the RRC layer of the eNB 200. The RRC layer controls the logical channel, the transport channel, and the physical channel according to establishment, re-establishment, and release of the radio bearer. If there is an RRC connection between the RRC of the UE 100 and the RRC of the eNB 200, the UE 100 is in a connected state (RRC connected state), and otherwise, the UE 100 is in an idle state (RRC idle state).

  A NAS (Non-Access Stratum) layer located above the RRC layer performs session management, mobility management, and the like.

  FIG. 5 is a configuration diagram of a radio frame used in the LTE system. In the LTE system, OFDMA (Orthogonal Frequency Division Multiplexing Access) is applied to the downlink and SC-FDMA (Single Carrier Frequency Multiple Access) is applied to the uplink.

  As shown in FIG. 5, the radio frame is composed of 10 subframes arranged in the time direction, and each subframe is composed of two slots arranged in the time direction. The length of each subframe is 1 ms, and the length of each slot is 0.5 ms. Each subframe includes a plurality of resource blocks (RB) in the frequency direction and includes a plurality of symbols in the time direction. A guard interval called a cyclic prefix (CP) is provided at the head of each symbol. The resource block includes a plurality of subcarriers in the frequency direction. A minimum resource unit composed of one subcarrier and one symbol is called a resource element (RE).

  Further, among radio resources allocated to the UE 100, a frequency resource can be specified by a resource block, and a time resource can be specified by a subframe (or slot).

  In the uplink, both ends in the frequency direction in each subframe are control regions mainly used as a physical uplink control channel (PUCCH). Further, the central portion in the frequency direction in each subframe is an area that can be used mainly as a physical uplink shared channel (PUSCH). Furthermore, a sounding reference signal (SRS) is arranged in each subframe.

  FIG. 6 is a configuration diagram of a radio frame used in the downlink.

  As shown in FIG. 6, in the downlink, the section of the first few symbols of each subframe is a control region mainly used as a physical downlink control channel (PDCCH). The remaining section of each subframe is an area that can be used mainly as a physical downlink shared channel (PDSCH).

  In the downlink, downlink reference signals such as a cell-specific reference signal (CRS) and / or a channel state information reference signal (CSI-RS) are distributed and arranged in each subframe. The downlink reference signal is configured by a predetermined orthogonal signal sequence and is arranged in a predetermined resource element.

(Outline of cooperative interference cancellation method)
FIG. 7 is a diagram for explaining the outline of the cooperative interference cancellation method according to the present embodiment.

  As illustrated in FIG. 7, the UE 100-1 is a UE to which a cooperative interference cancellation scheme is applied. UE100-1 has established the connection (RRC connection) with the cell which eNB200-1 manages. That is, the cell managed by the eNB 200-1 corresponds to the serving cell of the UE 100-1.

  In the present embodiment, an adjacent cell adjacent to the serving cell is managed by an eNB 200-2 that is different from the eNB 200-1. In the example of FIG. 7, UE100-2 has established the connection (RRC connection) with the cell which eNB200-2 manages. Note that the eNB 200-1 and the eNB 200-2 are synchronized.

  eNB200-1 and eNB200-2 are mutually connected by X2 interface. Moreover, eNB200-1 and eNB200-2 are connected with MME / S-GW300 by S1 interface.

  UE100-1 is located in the vicinity of the boundary of the cell (serving cell) which eNB200-1 manages, and the cell (adjacent cell) which eNB200-2 manages. Therefore, when eNB 200-2 performs transmission to UE 100-2 using the same radio resource as eNB 200-1, UE 100-1 receives downlink interference from eNB 200-2. That is, UE100-1 receives the desired wave signal from a serving cell, and receives the interference wave signal from an adjacent cell.

  In such an operating environment, the eNB 200-1 generates an interference replica signal corresponding to the interference wave signal, and superimposes the interference replica signal on the desired wave signal. And eNB200-1 transmits the desired wave signal with which the interference replica signal was superimposed to UE100-1.

  Here, the eNB 200-1 generates the interference replica signal so that the interference replica signal received by the UE 100-1 cancels the interference wave signal received by the UE 100-1. Specifically, the eNB 200-1 generates the interference replica signal so that the phase of the interference replica signal received by the UE 100-1 is opposite to the phase of the interference wave signal received by the UE 100-1. Moreover, eNB200-1 produces | generates an interference replica signal so that the amplitude of the interference replica signal which UE100-1 receives becomes the same as the amplitude of the interference wave signal which UE100-1 receives.

  As a result, the interference replica signal is synthesized in the opposite phase to the interference wave signal at the position of the UE 100-1 to cancel the interference wave signal. Therefore, since the reception power of the interference wave signal in UE 100-1 can be reduced, SIR can be improved. In addition, since it is not necessary to secure radio resources for the UE 100-1 in the adjacent cell, it is possible to improve the utilization efficiency of radio resources compared to JT-CoMP, DPS-CoMP, and CS-CoMP. Further, even when the eNB 200-2 does not have a plurality of antennas, that is, when beam forming / null steering is not possible, this method (cooperative interference cancellation method) can be applied.

  Further, the interference replica signal remains without being synthesized in the opposite phase to the interference wave signal at a position other than the position of the UE 100-1. Therefore, the interference replica signal also functions as an interference signal that interferes with demodulation of the desired wave signal at a position other than the position of the UE 100-1. Therefore, according to the cooperative interference cancellation method, the confidentiality of communication can be improved.

  eNB200-1 acquires at least one part of information required in order to produce | generate an interference replica signal from at least one of eNB200-2, MME / S-GW300, and UE100-1.

  In order to generate an interference replica signal, first, information (interference wave information) regarding the signal waveform of the interference wave signal transmitted by the eNB 200-2 is required.

  However, the interference wave signal transmitted by the eNB 200-2 is received by the UE 100-1 under the influence of the channel characteristics between the eNB 200-2 and the UE 100-1. Therefore, in order to generate an interference replica signal, secondly, information (channel information) regarding channel characteristics between the eNB 200-2 and the UE 100-1 is necessary.

  Furthermore, in order to improve the accuracy of the interference replica signal, information other than the interference wave information and the channel information can be used. Details of such information will be described later.

(Configuration of eNB 200-1)
FIG. 8 is a block diagram of the eNB 200-1 for realizing the cooperative interference cancellation scheme.

  As illustrated in FIG. 8, the processor 240 includes a desired wave signal generation unit 241 that generates a desired wave signal, an interference replica signal generation unit 242 that generates an interference replica signal, and a superposition that superimposes the interference replica signal on the desired wave signal. And an OFDM signal generation unit 244 that generates an OFDM signal (superimposed signal) from the desired wave signal on which the interference replica signal is superimposed. The radio signal transceiver 210 includes a transmitter 211 that amplifies and transmits an OFDM signal (superimposed signal).

  The desired wave signal generation unit 241 converts transmission data to the UE 100-1 into a desired wave signal by performing transmission processing on transmission data (user data) to the UE 100-1. The transmission process includes an encoding process, a modulation process, a precoding process, and a resource mapping process.

  The encoding process is a process for encoding transmission data. The encoding process may include a process of adding an error detection code (CRC code) to transmission data, a scramble process, and the like.

  The modulation process is a process of modulating encoded transmission data (encoded data).

  The precoding process is a process of precoding modulated encoded data (desired wave signal waveform) based on channel information indicating channel characteristics between the eNB 200-1 and the UE 100-1.

  In the following, channel information indicating channel characteristics between the eNB 200-1 and the UE 100-1 is referred to as “channel information 1”, and channel information indicating channel characteristics between the eNB 200-2 and the UE 100-1 is referred to as “channel information 1”. This is referred to as “channel information 2”.

  The resource mapping process is a process for mapping a pre-coded desired wave signal waveform to a physical resource.

  As a result of these processes, the desired wave signal generation unit 241 outputs the desired wave signal to the superimposing unit 243.

  The interference replica signal generation unit 242 generates an interference replica signal by adjusting the phase and amplitude of the interference wave signal waveform corresponding to the interference wave information based on at least the channel information 2. Further, the interference replica signal generation unit 242 generates an interference replica signal in consideration of information for improving the accuracy of the interference replica signal. Further, the interference replica signal generation unit 242 may adjust the transmission power in the radio transceiver 210.

  Specifically, the interference replica signal generation unit 242 generates the interference replica signal so that the phase of the interference replica signal received by the UE 100-1 is opposite to the phase of the interference wave signal received by the UE 100-1. . Moreover, eNB200-1 produces | generates an interference replica signal so that the amplitude of the interference replica signal which UE100-1 receives becomes the same as the amplitude of the interference wave signal which UE100-1 receives.

  For example, the interference replica signal generation unit 242 estimates the interference wave reception waveform received by the UE 100-1 using the interference wave information and the channel information 2. Next, the interference replica signal generation unit 242 maps (vectorizes) the interference wave reception waveform on the phase plane, rotates the phase by 180 degrees while keeping the amplitude constant, and thereby generates an interference replica signal (replica vector). ) Is generated. However, it is necessary to generate a replica so that the resource element position can be taken into consideration in consideration of the difference in CRS position and the presence or absence of DMRS (demodulation reference signal). Further, no replica is superimposed on the CRS position of the serving cell.

  First, a method for acquiring interference wave information will be described. The interference wave information is, for example, an interference wave signal waveform. The interference wave signal waveform is a waveform of a signal after modulation in the eNB 200-2. Alternatively, when it is possible to acquire a signal waveform (inverse characteristic interference signal waveform) having the same phase and the same amplitude as the interference wave signal waveform, the interference wave information may be an inverse characteristic interference signal.

  When the interference wave information is an interference wave signal waveform or a reverse characteristic interference signal waveform, the network interface 220 of the eNB 200-1 receives the interference wave signal waveform or the reverse characteristic interference signal waveform from the eNB 200-1. Then, the interference replica signal generation unit 242 acquires the interference wave signal waveform or inverse characteristic interference signal waveform received by the network interface 220.

  Alternatively, the interference wave information is transmission data (user data to the UE 100-2) before being converted into an interference wave signal in the eNB 200-2. The transmission data may be transmission data before encoding or may be transmission data after encoding.

  In the following, transmission data for UE 100-1 is referred to as “transmission data 1”, and transmission data for UE 100-2 is referred to as “transmission data 2”.

  When the interference wave information is transmission data 2, the network interface 220 of the eNB 200-1 receives the transmission data 2 from the eNB 200-1 or the MME / S-GW 300. The interference replica signal generation unit 242 acquires the transmission data 2 received by the network interface 220.

  When the interference wave information is transmission data 2, the interference replica signal generation unit 242 needs to perform the same transmission process as the transmission process performed on the transmission data 2 by the eNB 200-2 to generate an interference wave signal waveform. There is. Therefore, the network interface 220 of the eNB 200-1 receives transmission processing information indicating the content of the transmission processing performed by the eNB 200-2 on the transmission data 2 from the eNB 200-2. The contents of the transmission process are, for example, the contents of the encoding process, the contents of the modulation process, and the contents of the resource mapping process. The interference replica signal generation unit 242 acquires the transmission processing information received by the network interface 220.

  Second, a method for acquiring channel information 2 will be described. Since channel information 2 is information indicating downlink channel characteristics, in the case of FDD, channel information 2 is generated in UE 100-1. On the other hand, in the case of TDD, channel information 2 is generated in the UE 100-1 or the eNB 200-2.

  It should be noted that the interference replica signal generation unit 242 does not need to acquire the channel information 2 when the interference wave information is an inverse characteristic interference signal waveform.

  When generating the channel information 2 in the UE 100-1, the channel information 2 may be transmitted directly from the UE 100-1 to the eNB 200-1, and indirectly from the UE 100-1 to the eNB 200-1 via the eNB 200-2. May be transmitted automatically.

  The network interface 220 of the eNB 200-1 receives the channel information 2 from the eNB 200-2. Alternatively, the radio transceiver 210 of the eNB 200-1 receives the channel information 2 from the UE 100-1. The interference replica signal generation unit 242 acquires the channel information 2 received by the network interface 220 or the wireless transceiver 210.

  Third, a method for acquiring information for improving the accuracy of the interference replica signal will be described.

  Information for improving the accuracy of the interference replica signal is reception power information indicating reception power (RSRP; Reference Signal Received Power) for a reference signal received by the UE 100-1 from the eNB 200-2. The interference replica signal generation unit 242 can appropriately adjust the amplitude (including transmission power) of the interference replica signal by taking the received power information into consideration.

  Received power information is generated in UE 100-1. The received power information may be directly transmitted from the UE 100-1 to the eNB 200-1, or may be indirectly transmitted from the UE 100-1 to the eNB 200-1 via the eNB 200-2.

  The network interface 220 of the eNB 200-1 receives the received power information from the eNB 200-2. Alternatively, the radio transceiver 210 of the eNB 200-1 receives reception power information from the UE 100-1. The interference replica signal generation unit 242 acquires received power information received by the network interface 220 or the wireless transceiver 210.

  Alternatively, the information for improving the accuracy of the interference replica signal is difference information indicating at least one of an amplitude difference or a phase difference between the reference signal (CRS) transmitted by the eNB 200-2 and the data signal. The data signal is a signal that the eNB 200-2 transmits on the physical downlink shared channel (PDSCH). The interference replica signal generation unit 242 can appropriately adjust the amplitude and / or phase of the interference replica signal by adding the difference information.

  The difference information is generated in the eNB 200-2. The eNB 200-2 transmits the difference information to the eNB 200-1. The network interface 220 of the eNB 200-1 receives the difference information from the eNB 200-2. The interference replica signal generation unit 242 acquires difference information received by the network interface 220.

  Or the information for improving the precision of an interference replica signal is power difference information which shows the power difference between the reference signal (CRS) and data signal which eNB200-2 transmits. The interference replica signal generation unit 242 can appropriately adjust the amplitude (including transmission power) of the interference replica signal by taking into account the power difference information.

  The power difference information is, for example, power difference information (information indicating a transmission power difference) generated in the eNB 200-2. The power difference information may be directly transmitted from the eNB 200-2 to the eNB 200-1, or may be indirectly transmitted from the eNB 200-2 to the eNB 200-1 via the UE 100-1.

  The network interface 220 of the eNB 200-1 receives the power difference information from the eNB 200-2. Alternatively, the radio transceiver 210 of the eNB 200-1 receives the power difference information from the UE 100-1. The interference replica signal generation unit 242 acquires the power difference information received by the network interface 220 or the wireless transceiver 210.

  Alternatively, the information for improving the accuracy of the interference replica signal is time difference information indicating a delay time difference between the delay time from the eNB 200-1 to the UE 100-1 and the delay time from the eNB 200-2 to the UE 100-1. It is. The interference replica signal generation unit 242 can appropriately adjust the transmission timing of the interference replica signal by adding the time difference information.

  The time difference information is generated in the UE 100-1. The time difference information may be transmitted directly from the UE 100-1 to the eNB 200-1, or may be indirectly transmitted from the UE 100-1 to the eNB 200-1 via the eNB 200-2.

  The network interface 220 of the eNB 200-1 receives the time difference information from the eNB 200-2. Or the radio | wireless transmitter / receiver 210 of eNB200-1 receives time difference information from UE100-1. The interference replica signal generation unit 242 acquires time difference information received by the network interface 220 or the wireless transceiver 210.

(Operation according to the first embodiment)
Hereinafter, the operation according to the present embodiment will be described in the order of the operation pattern 1 to the operation pattern 8.

(1) Operation pattern 1
FIG. 9 is a sequence diagram of the operation pattern 1 according to the present embodiment. In the operation pattern 1, the interference wave information acquired by the eNB 200-1 is an interference signal waveform.

  As illustrated in FIG. 9, in step S1101, the eNB 200-2 performs scheduling (or pre-scheduling) for the UE 100-2 connected to the own cell.

  In step S1102, the eNB 200-2 generates a transmission signal waveform from the transmission data 2 based on the scheduling result, and samples the transmission signal waveform.

  In step S1103, the eNB 200-2 transmits the sampled transmission signal waveform to the eNB 200-1. Here, the sampled transmission signal waveform corresponds to an interference signal waveform.

  In step S1104, the eNB 200-1 performs scheduling for the UE 100-1 connected to the own cell, and generates a transmission signal waveform (desired wave signal waveform).

  In step S1105, the eNB 200-1 acquires channel information 2. A specific example of the operation for the eNB 200-1 to acquire the channel information 2 will be described later.

  In step S1106, based on the channel information 2, the eNB 200-1 generates an inverse characteristic signal of the interference signal waveform as an interference replica signal. And eNB200-1 superimposes an interference replica signal on a desired wave signal.

In step S1107, ENB200-2 performs transmission to UE100- 2. UE100-1 receives the signal from eNB200-2 as an interference wave signal. On the other hand, the eNB 200-1 transmits a superimposed signal to the UE 100-1. The UE 100-1 receives the superimposed signal. Here, the interference wave signal is canceled by the interference replica signal included in the superimposed signal.

  In step S1108, the UE 100-1 demodulates the desired wave signal included in the superimposed signal.

  In this operation pattern, it is assumed that the interference wave signal is canceled mainly at the UE receiving end (wireless signal state), but may be canceled at the time of demodulation (baseband signal state). The same applies to the following operation patterns.

  FIG. 10 is a sequence diagram of Operation Example 1 for the eNB 200-1 to acquire the channel information 2. In this operation example, the channel information 2 is generated in the UE 100-1 and transmitted from the UE 100-1 to the eNB 200-1 via the eNB 200-2.

  As illustrated in FIG. 10, in step S11, the eNB 200-1 transmits the identifier (terminal ID) of the UE 100-1 to which the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S12, the eNB 200-1 transmits, to the UE 100-1, the identifier (cell ID) of the neighboring cell from which the UE 100-1 should obtain the channel information 2. The cell ID corresponds to cell designation information indicating a cell to be estimated for channel characteristics.

  In step S13, the eNB 200-2 transmits a reference signal (CRS).

  In step S14, the UE 100-1 receives the reference signal (CRS) from the eNB 200-2 based on the cell ID received from the eNB 200-1. Then, the UE 100-1 performs channel estimation based on the CRS and generates channel information 2. Thus, UE100-1 produces | generates the channel information 2 by estimating a channel characteristic about the cell which cell ID received from eNB200-1 shows.

  In step S15, the UE 100-1 transmits the channel information 2 to the eNB 200-2 based on the cell ID received from the eNB 200-1. Here, the UE 100-1 adds its own terminal ID to the channel information 2 and transmits it.

  In step S16, eNB200-2 transfers the channel information 2 received from UE100-1 to eNB200-1 based on terminal ID received from eNB200-1. The eNB 200-1 receives the channel information 2 from the eNB 200-2.

  FIG. 11 is a sequence diagram of Operation Example 2 for the eNB 200-1 to acquire the channel information 2. In this operation example, the channel information 2 is generated in the UE 100-1 and transmitted directly from the UE 100-1 to the eNB 200-1.

  As illustrated in FIG. 11, in step S21, the eNB 200-1 transmits, to the UE 100-1, the identifier (cell ID) of the neighboring cell from which the UE 100-1 should obtain the channel information 2. The cell ID corresponds to cell designation information indicating a cell to be estimated for channel characteristics.

  In step S22, the eNB 200-2 transmits a reference signal (CRS).

  In step S23, the UE 100-1 receives the reference signal (CRS) from the eNB 200-2 based on the cell ID received from the eNB 200-1. Then, the UE 100-1 performs channel estimation based on the CRS and generates channel information 2. Thus, UE100-1 produces | generates the channel information 2 by estimating a channel characteristic about the cell which cell ID received from eNB200-1 shows.

  In step S24, the UE 100-1 transmits the channel information 2 to the eNB 200-1 based on the cell ID received from the eNB 200-1. The eNB 200-1 receives the channel information 2 from the UE 100-1.

  FIG. 12 is a sequence diagram of Operation Example 3 for the eNB 200-1 to acquire the channel information 2. In this operation example, the channel information 2 is generated in the eNB 200-2 and transmitted from the eNB 200-2 to the eNB 200-1.

  As illustrated in FIG. 12, in step S31, the eNB 200-1 transmits the identifier (terminal ID) of the UE 100-1 to which the cooperative interference cancellation scheme is applied to the eNB 200-2. The terminal ID corresponds to terminal designation information indicating a UE to be estimated for channel characteristics.

  In step S32, eNB200-1 transmits the information for SRS demodulation for demodulating the reference signal (SRS) which UE100-1 transmits to eNB200-2. The SRS demodulation information includes the SRS insertion subframe interval, the orthogonal code of the target UE, the SRS bandwidth, the SRS frequency domain position, the SRS hopping band, and the like. The information for SRS demodulation may further include a subframe start position and a system bandwidth. In addition, eNB200-1 may include said terminal ID in the information for SRS demodulation, and may transmit to eNB200-2. In this case, step S31 can be omitted.

  In step S33, the UE 100-1 transmits a reference signal (SRS).

  In step S34, the eNB 200-2 receives and demodulates the reference signal (SRS) from the UE 100-1 based on the SRS demodulation information received from the eNB 200-1. Then, the eNB 200-2 performs channel estimation based on the SRS and generates channel information 2.

  In step S35, the eNB 200-2 transmits the channel information 2 to the eNB 200-1. The eNB 200-1 receives the channel information 2 from the eNB 200-2.

(2) Operation pattern 2
FIG. 13 is a sequence diagram of an operation pattern 2 according to the present embodiment. The operation pattern 2 is obtained by partially changing the operation pattern 1.

  As shown in FIG. 13, in step S1201, the eNB 200-1 performs scheduling (or pre-scheduling) for the UE 100-1 connected to the own cell.

  In step S1202, eNB200-1 transmits the resource information which shows the allocation resource block with respect to UE100-1 to eNB200-2 based on the result of scheduling. The resource information corresponds to information indicating a radio resource used for transmitting a desired wave signal.

  In step S1203, eNB200-2 performs scheduling with respect to UE100-2 connected to an own cell.

  In step S1204, the eNB 200-2 generates a transmission signal waveform from the transmission data 2 for the resource block corresponding to the resource information received from the eNB 200-1 based on the scheduling result, and samples the transmission signal waveform.

  In step S1205, the eNB 200-2 transmits the sampled transmission signal waveform to the eNB 200-1. Here, the sampled transmission signal waveform corresponds to an interference signal waveform.

  In step S1206, the eNB 200-1 acquires channel information 2. An operation example for acquiring the channel information 2 is the same as the operation pattern 1 described above.

  In step S1207, the eNB 200-1 generates an inverse characteristic signal of the desired signal waveform as an interference replica signal based on the channel information 2. And eNB200-1 superimposes an interference replica signal on a desired wave signal.

In step S1208, ENB200-2 performs transmission to UE100- 2. UE100-1 receives the signal from eNB200-2 as an interference wave signal. On the other hand, the eNB 200-1 transmits a superimposed signal to the UE 100-1. The UE 100-1 receives the superimposed signal. Here, the interference wave signal is canceled by the interference replica signal included in the superimposed signal.

  In step S1209, the UE 100-1 demodulates the desired wave signal included in the superimposed signal.

(3) Operation pattern 3
FIG. 14 is a sequence diagram of an operation pattern 3 according to the present embodiment. In the operation pattern 3, the interference wave information acquired by the eNB 200-1 is a reverse characteristic interference signal waveform.

  As shown in FIG. 14, in step S1301, the eNB 200-2 acquires channel information 2 from the UE 100-1. Alternatively, the eNB 200-2 may acquire the channel information 2 by itself.

  In step S1302, the eNB 200-2 performs scheduling (or pre-scheduling) for the UE 100-2 connected to the own cell.

  In step S1303, the eNB 200-2 generates a transmission signal waveform (interference wave signal waveform) from the transmission data 2 based on the scheduling result.

  In step S1304, the eNB 200-2 generates an inverse characteristic of the interference wave signal waveform as an inverse characteristic interference waveform based on the channel information 2, and samples the inverse characteristic interference waveform.

  In step S1305, the eNB 200-2 transmits the sampled reverse characteristic interference waveform to the eNB 200-1.

  Note that, similarly to the operation pattern 2 described above, waveform notification may be performed based on resource information. Specifically, before step S1302, the eNB 200-1 transmits resource information indicating an allocation resource block for the UE 100-1 to the eNB 200-2, and the eNB 200-2 transmits a resource block corresponding to the resource information. A signal waveform is generated and sampled. As a result, there is an advantage that the amount of signal transmitted on the X2 interface is reduced and the eNB 200-1 only needs to superimpose the reverse characteristic signal.

  In step S1306, the eNB 200-1 performs scheduling for the UE 100-1 connected to the own cell, and generates a transmission signal waveform (desired wave signal waveform).

  In step S1307, eNB200-1 produces | generates an interference replica signal with the reverse characteristic interference waveform received from eNB200-2. And eNB200-1 superimposes an interference replica signal on a desired wave signal.

In step S1308, ENB200-2 performs transmission to UE100- 2. UE100-1 receives the signal from eNB200-2 as an interference wave signal. On the other hand, the eNB 200-1 transmits a superimposed signal to the UE 100-1. The UE 100-1 receives the superimposed signal. Here, the interference wave signal is canceled by the interference replica signal included in the superimposed signal.

  In step S1309, the UE 100-1 demodulates the desired wave signal included in the superimposed signal.

(4) Operation pattern 4
FIG. 15 is a sequence diagram of the operation pattern 4 according to the present embodiment. In the operation pattern 4, the interference wave information acquired by the eNB 200-1 is transmission data (transmission data 2) for the UE 100-2.

  As illustrated in FIG. 15, in step S1401, the eNB 200-1 performs scheduling (or pre-scheduling) for the UE 100-1 connected to the own cell.

  In step S1402, eNB200-1 produces | generates a transmission signal waveform (desired wave signal waveform) from the transmission data (transmission data 1) with respect to UE100-1 based on the result of scheduling.

  In step S1403, the eNB 200-2 transmits the transmission data 2 to the eNB 200-1.

  Note that, similarly to the operation pattern 2 described above, data notification may be performed based on resource information. Specifically, before step S1403, the eNB 200-1 transmits resource information indicating the allocated resource block for the UE 100-1 to the eNB 200-2, and the eNB 200-2 transmits the transmission data 2 corresponding to the resource information. It transmits to eNB200-2. Thereby, the amount of signals transmitted on the X2 interface can be reduced.

  In step S1404, the eNB 200-2 performs scheduling (or pre-scheduling) for the UE 100-2 connected to the own cell.

  In step S1405, the eNB 200-2 transmits scheduling information to the eNB 200-1 based on the scheduling result. The scheduling information corresponds to transmission processing information indicating the content of transmission processing when the transmission data 2 is converted into a transmission signal (interference wave signal).

  In step S1406, the eNB 200-1 acquires channel information 2. The operation for the eNB 200-1 to acquire the channel information 2 is the same as the operation pattern 1 described above.

  In step S1407, eNB200-2 transmits the difference information which shows at least one of the amplitude difference or phase difference between the reference signal (CRS) and data signal which eNB200-2 transmits to eNB200-1. The eNB 200-2 may transmit the difference information for each resource block to the eNB 200-1.

  Note that the transmission of difference information from the eNB 200-2 to the eNB 200-1 is not limited to this operation pattern, and can be applied to the above-described operation patterns and operation patterns described later. Further, when the allocation resource block for the UE 100-1 is notified from the eNB 200-1 to the eNB 200-2 as in the operation pattern 2 described above, the eNB 200-2 transmits the difference information only for the allocation resource block to the eNB 200-. 1 may be transmitted.

  In step S1408, the eNB 200-2 generates a transmission signal waveform (interference wave signal waveform) from the transmission data 2 based on the result of scheduling (step S1404).

  In step S1409, eNB200-1 performs the transmission process which the scheduling information (transmission process information) received from eNB200-2 performs with respect to the transmission data 2 received from eNB200-2, and produces | generates an interference signal waveform.

  In step S1410, eNB200-1 produces | generates the reverse characteristic signal of an interference signal waveform as an interference replica signal based on the channel information 2. FIG. In that case, eNB200-1 adjusts the phase and amplitude of an interference replica signal based on the difference information received from eNB200-2.

  In step S1411, the eNB 200-1 superimposes the interference replica signal on the desired wave signal.

In step S1412, ENB200-2 performs transmission to UE100- 2. UE100-1 receives the signal from eNB200-2 as an interference wave signal. On the other hand, the eNB 200-1 transmits a superimposed signal to the UE 100-1. The UE 100-1 receives the superimposed signal. Here, the interference wave signal is canceled by the interference replica signal included in the superimposed signal.

  In step S1413, the UE 100-1 demodulates the desired wave signal included in the superimposed signal.

(5) Operation pattern 5
FIG. 16 is a sequence diagram of an operation pattern 5 according to the present embodiment. The operation pattern 5 is obtained by partially changing the operation pattern 4.

  As illustrated in FIG. 16, in step S1501, the eNB 200-1 performs scheduling (or pre-scheduling) for the UE 100-1 connected to the own cell.

  In step S1502, eNB200-1 produces | generates a transmission signal waveform (desired wave signal waveform) from the transmission data (transmission data 1) with respect to UE100-1 based on the result of scheduling.

  In step S1503, the S-GW 300 transmits the transmission data 2 to the eNB 200-1 and the eNB 200-2. In this operation pattern, the S-GW 300 corresponds to a management device.

  In step S1504, the eNB 200-2 performs scheduling (or pre-scheduling) for the UE 100-2 connected to the own cell.

  In step S1505, the eNB 200-2 transmits scheduling information to the eNB 200-1 based on the scheduling result. The scheduling information corresponds to transmission processing information indicating the content of transmission processing when the transmission data 2 is converted into a transmission signal (interference wave signal).

  In step S1506, the eNB 200-1 acquires channel information 2. The operation for the eNB 200-1 to acquire the channel information 2 is the same as the operation pattern 1 described above.

  In step S1507, eNB200-2 produces | generates a transmission signal waveform (interference wave signal waveform) from the transmission data 2 based on the result of scheduling (step S1504).

  In step S1508, eNB200-1 performs the transmission process which the scheduling information (transmission process information) received from eNB200-2 performs with respect to the transmission data 2 received from eNB200-2, and produces | generates an interference signal waveform.

  In step S1509, eNB200-1 produces | generates the reverse characteristic signal of an interference signal waveform as an interference replica signal based on the channel information 2. FIG.

  In step S1510, the eNB 200-1 superimposes the interference replica signal on the desired wave signal.

In step S1511, ENB200-2 performs transmission to UE100- 2. UE100-1 receives the signal from eNB200-2 as an interference wave signal. On the other hand, the eNB 200-1 transmits a superimposed signal to the UE 100-1. The UE 100-1 receives the superimposed signal. Here, the interference wave signal is canceled by the interference replica signal included in the superimposed signal.

  In step S1512, the UE 100-1 demodulates the desired wave signal included in the superimposed signal.

(6) Operation pattern 6
FIG. 17 is a sequence diagram of an operation pattern 6 according to the present embodiment. The operation pattern 6 is an operation pattern for appropriately adjusting the amplitude of the interference replica signal. The operation pattern 6 is implemented in combination with any of the operation patterns 1 to 5 described above.

  As illustrated in FIG. 17, in step S1601, the eNB 200-1 transmits a reference signal (CRS). The UE 100-1 receives the CRS.

  In step S1602, the UE 100-1 measures the received power (RSRP1) of the CRS received from the eNB 200-1.

  In step S1603, UE100-1 transmits RSRP1 (RSRP report) to eNB200-1.

  In step S1604, eNB200-1 calculates the propagation loss (propagation loss 1) between UE100-1 and eNB200-1 by subtracting RSRP1 from the transmission power of CRS.

  In step S1605, the eNB 200-1 adjusts the amplitude of the desired wave signal based on the propagation loss 1.

  In step S1606, the eNB 200-2 transmits the CRS. The UE 100-1 receives the CRS.

  In step S1607, the UE 100-1 measures the received power (RSRP2) of the CRS received from the eNB 200-2.

  In step S1608, the UE 100-1 transmits RSRP2 to the eNB 200-2.

  In step S1609, eNB200-2 transfers RSRP2 received from UE100-1 to eNB200-1. Here, the eNB 200-2 may transfer RSRP2 to the eNB 200-1 in response to a prior request from the eNB 200-1.

  In addition, UE100-1 may transmit RSRP2 directly to eNB200-1, instead of transmitting RSRP2 to eNB200-2.

  In step S1610, eNB200-1 calculates the propagation loss (propagation loss 2) between UE100-1 and eNB200-2 by subtracting RSRP2 from the transmission power of CRS.

  In step S1611, the eNB 200-1 adjusts the amplitude of the interference replica signal based on the propagation loss 2.

  In addition, when eNB200-1 and / or eNB200-2 transmit reference signals other than CRS (specifically, CSI-RS), UE100-1 also measures the received power of CSI-RS, CSI-RS May be transmitted to eNB 200-1 or eNB 200-2. In this case, information indicating the type of received power (CRS or CSI-RS) may be added.

(7) Operation pattern 7
FIG. 18 is a sequence diagram of the operation pattern 7 according to the present embodiment. The operation pattern 7 is an operation pattern for appropriately adjusting the amplitude of the interference replica signal. The operation pattern 7 is implemented in combination with any of the operation patterns 1 to 5 described above.

  As illustrated in FIG. 18, in step S1701, the eNB 200-1 transmits an identifier (cell ID) of a neighboring cell (cell managed by the eNB 200-2) to the UE 100-1.

  In step S1702, UE100-1 receives the system information (SIB; System Information Block) which eNB200-2 transmits based on cell ID received from eNB200-1. In this operation pattern, the SIB includes power difference information indicating a power difference (transmission power difference) between the reference signal and the data signal transmitted by the eNB 200-2.

  In step S1703, the UE 100-1 demodulates the SIB and acquires power difference information included in the SIB.

  In step S1704, the UE 100-1 transmits the power difference information to the eNB 200-1.

  In step S1705, the eNB 200-1 adjusts the amplitude of the interference replica signal based on the power difference information received from the UE 100-1.

  In this operation pattern, the power difference information is transmitted from the eNB 200-2 to the eNB 200-1 via the UE 100-1, but may be transmitted directly from the eNB 200-2 to the eNB 200-1. In this case, the eNB 200-2 may transmit the power difference information to the eNB 200-1 in response to a request from the eNB 200-1.

(8) Operation pattern 8
FIG. 19 is a sequence diagram of the operation pattern 8 according to the present embodiment. The operation pattern 8 is an operation pattern for appropriately adjusting the transmission timing (superimposition timing) of the interference replica signal. The operation pattern 8 is implemented in combination with any of the operation patterns 1 to 5 described above.

  As illustrated in FIG. 19, in step S1801, the eNB 200-1 transmits a reference signal (CRS). The CRS transmitted by the eNB 200-1 is received by the UE 100-1 after the propagation delay τs.

  In step S1802, the eNB 200-2 transmits the CRS at the same time as the eNB 200-1 transmits the CRS. The CRS transmitted by the eNB 200-2 is received by the UE 100-1 after the propagation delay τn.

  In step S1803, the UE 100-1 generates a difference between the reception timing of the CRS from the eNB 200-1 and the reception timing of the CRS from the eNB 200-2 as time difference information. That is, the time difference information is information indicating a delay time difference between the delay time τs from the eNB 200-1 to the UE 100-1 and the delay time τn from the eNB 200-2 to the UE 100-1.

  In step S1804, the UE 100-1 transmits time difference information to the eNB 200-1. eNB200-1 adjusts the transmission timing (superimposition timing) of an interference replica signal based on the time difference information received from UE100-1.

  In this operation pattern, the eNB 200-1 and the eNB 200-2 transmit the CRS at the same time, but when the transmission timing of the CRS is different, the information on the transmission timing difference is shared between the eNB 200-1 and the eNB 200-2. The time difference information received from the UE 100-1 may be corrected. Alternatively, when information on the transmission timing difference (subframe number difference, symbol number difference, etc.) is known on the UE 100-1 side, the UE 100-1 may correct the delay time and report the delay time difference.

  In this operation pattern, CRS is used as a reference signal, but CSI-RS may be used instead of CRS. Furthermore, UE100-1 may transmit the information which shows the difference of the reception power of CRS from eNB200-1, and the reception power of CRS from eNB200-2 with time difference information.

[Second Embodiment]
Hereinafter, the difference between the second embodiment and the first embodiment will be mainly described.

  In the first embodiment described above, it is assumed that a cooperative interference cancellation method (a method of superimposing an interference replica signal on a desired wave signal) is always applied.

  On the other hand, in the second embodiment, the cooperative interference cancellation method is applied only when a predetermined condition is satisfied.

(1) Operation pattern 1
FIG. 20 is a sequence diagram of operation pattern 1 according to the present embodiment. In this operation pattern, the eNB 200-1 determines whether or not to apply the cooperative interference cancellation scheme based on the number of antennas (transmission antennas) associated with the serving cell. Here, when the number of cells managed by the eNB 200-1 is one, the number of antennas associated with the serving cell is the number of antennas of the eNB 200-1. When there are a plurality of cells managed by the eNB 200-1 and the antennas are different for each cell, the number of antennas associated with the serving cell is the number of antennas of the serving cell.

  As illustrated in FIG. 20, in step S2101, the eNB 200-1 checks the number of antennas associated with the serving cell.

  In step S2102, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the number of antennas associated with the serving cell. For example, when the number of antennas associated with the serving cell is one, the eNB 200-1 determines that the cooperative interference cancellation scheme is applied because CB-CoMP is not applicable. Alternatively, the eNB 200-1 determines that the cooperative interference cancellation scheme is to be applied if there are a plurality of antennas associated with the serving cell and the number is not sufficient for beamforming / null steering. May be. Here, the description will be made assuming that it is determined that the cooperative interference cancellation method is applied.

  In step S2103, the eNB 200-1 transmits a notification to the effect that the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S2104, the eNB 200-2 transmits the interference wave information to the eNB 200-1 in response to the notification from the eNB 200-1.

(2) Operation pattern 2
FIG. 21 is a sequence diagram of an operation pattern 2 according to the present embodiment. In this operation pattern, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the received signal state in the UE 100-1. For example, the eNB 200-1 determines to apply the cooperative interference cancellation method when the received signal state (received SIR or the like) does not improve even when CB-CoMP is performed, for example.

  As shown in FIG. 21, in step S2201, the eNB 200-1 and the eNB 200-2 perform normal transmission.

  In step S2202, the UE 100-1 measures the reception SIR. However, not only the reception SIR but other reception quality indicators such as CQI may be used.

  In step S2203, the UE 100-1 transmits a reception SIR (SIR report) to the eNB 200-1.

  In step S2204, the eNB 200-1 and the eNB 200-2 perform transmission by CB-CoMP.

  In step S2205, the UE 100-1 measures the reception SIR. However, not only the reception SIR but other reception quality indicators such as CQI may be used.

  In step S2206, the UE 100-1 transmits a reception SIR (SIR report) to the eNB 200-1.

  In step S2207, the eNB 200-1 compares the reception SIR before CB-CoMP with the reception SIR in CB-CoMP.

  In step S2208, the eNB 200-1 determines whether or not the reception SIR in CB-CoMP is improved by a certain amount or more (including zero) than the reception SIR before CB-CoMP. Note that the certain amount may be shared by the eNB 200-1 and the eNB 200-2.

  When the reception SIR during CB-CoMP is improved over the reception SIR before CB-CoMP, the eNB 200-1 determines to continue CB-CoMP. On the other hand, when the reception SIR in CB-CoMP is not improved compared to the reception SIR before CB-CoMP, the eNB 200-1 determines to apply the cooperative interference cancellation scheme. Here, the description will be made assuming that it is determined that the cooperative interference cancellation method is applied.

  In step S2209, the eNB 200-1 transmits a notification to the effect that the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S2210, eNB200-2 transmits interference wave information to eNB200-1 according to the notification from eNB200-1.

(3) Operation pattern 3
FIG. 22 is a sequence diagram of operation pattern 3 according to the present embodiment. This operation pattern is common to the operation pattern 2 described above in that it is determined whether or not to apply the cooperative interference cancellation method based on the received signal state. However, in this operation pattern, the eNB 200-1 determines whether or not to apply the cooperative interference cancellation scheme based on the spatial characteristics (Spatial Signature) as the received signal state.

  As illustrated in FIG. 22, in step S2301, the eNB 200-1 and the eNB 200-2 perform normal transmission.

  In step S2302, UE100-1 measures the spatial characteristic which shows the spatial correlation (space separation degree) between the antennas in eNB200-2.

  In step S2303, UE100-1 transmits a spatial characteristic (Spatial Signature report) to eNB200-1.

  In step S2304, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the spatial characteristics. For example, when the eNB 200-1 determines that null steering is difficult based on spatial correlation (separation) between antennas in the eNB 200-2, the eNB 200-1 considers that CB-CoMP is not applicable, and sets the cooperative interference cancellation scheme. Determine to apply. Here, the description will be made assuming that it is determined that the cooperative interference cancellation method is applied.

  In step S2305, the eNB 200-1 transmits a notification to the effect that the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S2306, the eNB 200-2 transmits the interference wave information to the eNB 200-1 in response to the notification from the eNB 200-1.

  In this operation pattern, the spatial characteristics are measured by the UE 100-1, but in the case of TDD, the spatial characteristics may be measured by the eNB 200-2. In this case, step S2305 may be omitted and the notification of step S2305 may be included in step S2306.

(4) Operation pattern 4
FIG. 23 is a sequence diagram of the operation pattern 4 according to the present embodiment. In this operation pattern, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the state of the radio resource. In this operation pattern, in the initial state, the eNB 200-1 and the eNB 200-2 perform JT-CoMP or DPS-CoMP.

  As illustrated in FIG. 23, in step S2401, the eNB 200-2 checks the free radio resource of the own cell and determines whether the free radio resource is tight. Here, the description will proceed assuming that it is determined that the available radio resources are tight.

  In step S2402, the eNB 200-2 transmits a request for applying the cooperative interference cancellation scheme to the eNB 200-1.

  In step S2403, the eNB 200-1 determines to apply the cooperative interference cancellation scheme in response to a request from the eNB 200-2.

  In step S2404, the eNB 200-1 transmits a notification to the effect that the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S2405, the eNB 200-2 transmits the interference wave information to the eNB 200-1 in response to the notification from the eNB 200-1.

  In this operation pattern, it is determined whether or not to apply the cooperative interference cancellation method based on the available radio resources of the eNB 200-2. However, the following method may be used. Specifically, the eNB 200-1 or the eNB 200-2 applies a cooperative interference cancellation scheme in order to avoid interference when radio resources allocated to UEs located near the cell edge exceed a predetermined amount. May be.

(5) Operation pattern 5
FIG. 24 is a sequence diagram of an operation pattern 5 according to the present embodiment. In this operation pattern, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the QoS required by the UE 100-1.

  As illustrated in FIG. 24, in step S2501, the eNB 200-1 and the eNB 200-2 perform normal transmission. However, in this operation pattern, the eNB 200-1 and the eNB 200-2 may perform CB-CoMP.

  In step S2502, eNB200-1 confirms whether QoS which UE100-1 requires is satisfy | filled. Here, the QoS required by the UE 100-1 can be determined by the type of bearer.

  In step S2503, the eNB 200-1 determines whether to apply the cooperative interference cancellation scheme based on the QoS required by the UE 100-1. For example, the eNB 200-1 determines to apply the cooperative interference cancellation scheme when the QoS required by the UE 100-1 is not satisfied. Here, the description will be made assuming that it is determined that the cooperative interference cancellation method is applied.

  In step S2504, the eNB 200-1 transmits a notification to the effect that the cooperative interference cancellation scheme is applied to the eNB 200-2.

  In step S2505, the eNB 200-2 transmits the interference wave information to the eNB 200-1 in response to the notification from the eNB 200-1.

[Other Embodiments]
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In each of the above-described embodiments, the eNB 200-1 generates an OFDM signal from a desired wave signal on which an interference replica signal is superimposed, and transmits the generated OFDM signal, but is not limited thereto. For example, the eNB 200-1 may generate a signal such as a CDMA signal, an IDMA signal, an FDMA signal, or a TDMA signal from the desired wave signal on which the interference replica signal is superimposed, and transmit the generated signal.

  In each embodiment mentioned above, although a serving cell and an adjacent cell were managed by different eNB (eNB200-1, eNB200-2), even if a serving cell and an adjacent cell are managed by the same eNB (eNB200-1), Good. In addition, the present invention may be applied to the eNB 200-1 when the UE 100-1 and the UE 100-2 are in the same serving cell. Therefore, the eNB 200-1 may manage each of the communication with the UE 100-1 and the communication with the UE 100-2. For example, when eNB200-1 performs MU (Multi User) -MIMO (Multiple Input Multiple Output) which spatially multiplexes several UE100 (UE100-1 and UE100-2) by downlink multi-antenna transmission. The present invention may be applied. In these cases, since the eNB 200-1 controls transmission to the UE 100-2, information (for example, transmission data 2, an interference wave signal waveform, etc.) used for generating the interference replica signal is transmitted from the neighboring eNB. It can be used without receiving.

  In each of the above-described embodiments, an example in which the present invention is applied to the LTE system has been described. However, the present invention is not limited to the LTE system, and the present invention may be applied to a system other than the LTE system.

  US Provisional Application No. 61/740899 (filed on Dec. 21, 2012), U.S. Provisional Application No. 61/745016 (filed on Dec. 21, 2012), U.S. Provisional Application No. 61/745043 (Dec. 2012) The entire contents of US application No. 61/748293 (filed Jan. 2, 2013) and US Provisional Application No. 61/748293 are incorporated herein by reference.

  As described above, since the mobile communication system, the communication control method, the base station, the user terminal, and the processor according to the present invention can reduce the reception power of the interference wave signal in the user terminal, it is useful in the mobile communication field. is there.

Claims (49)

A user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal; and
A mobile communication system comprising: a first base station that manages the serving cell;
The first base station is
A controller that generates an interference replica signal corresponding to the interference wave signal and superimposes the interference replica signal on the desired wave signal;
A transmission unit that transmits the desired wave signal on which the interference replica signal is superimposed to the user terminal,
The mobile communication system, wherein the control unit generates the interference replica signal so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal. The other user terminal is connected to an adjacent cell adjacent to the serving cell;
The mobile communication system according to claim 1, wherein the interference wave signal is a signal from the adjacent cell. The first base station manages the serving cell to which the user terminal connects and the neighboring cell adjacent to the serving cell to which the other user terminal connects,
The mobile communication system according to claim 1, wherein the transmission unit transmits the interference wave signal to the other user terminal. The other user terminal is located in the serving cell to which the user terminal is connected,
The mobile communication system according to claim 1, wherein the transmission unit transmits the interference wave signal to the other user terminal. The first base station manages communication with the user terminal and communication with the other user terminal,
The mobile communication system according to claim 1, wherein the transmission unit transmits the interference wave signal to the other user terminal.   The control unit generates the interference replica signal so that a phase of the interference replica signal received by the user terminal is opposite to a phase of the interference wave signal received by the user terminal. The mobile communication system according to claim 1. The control unit generates the interference replica signal so that an amplitude of the interference replica signal received by the user terminal is the same as an amplitude of the interference wave signal received by the user terminal. The mobile communication system according to claim 1 . The first base station includes at least one antenna associated with the serving cell;
The mobile communication system according to claim 1, wherein the control unit determines whether or not to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on the number of antennas. .   2. The control unit according to claim 1, wherein the control unit determines whether to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on a reception signal state in the user terminal. Mobile communication system.   The control unit determines whether or not to apply superimposition transmission that superimposes the interference replica signal on the desired wave signal based on a usage state of radio resources in the mobile communication system. The mobile communication system according to 1.   The said control part determines whether the superimposition transmission which superimposes the said interference replica signal on the said desired wave signal is applied based on QoS which the said user terminal requires. Mobile communication system. A management device for managing the first base station;
The first base station includes a receiving unit that receives information used to generate the interference replica signal from at least one of the management device and the user terminal,
The mobile communication system according to claim 1, wherein the control unit generates the interference replica signal based on information received by the receiving unit. A second base station that manages a neighboring cell adjacent to the serving cell ;
The management device manages the second base station;
The reception unit receives information used to generate the interference replica signal from at least one of the second base station, the management device, and the user terminal. The mobile communication system described. Information used to generate the interference replica signal includes waveform information related to the signal waveform of the interference wave signal,
The second base station transmits the waveform information to the first base station;
The mobile communication system according to claim 13, wherein the receiving unit receives the waveform information. The control unit transmits resource information indicating a radio resource used for transmitting the desired signal to the second base station,
The mobile communication system according to claim 14, wherein the second base station transmits the waveform information to the first base station based on the resource information. The information used for generating the interference replica signal includes transmission data before being converted into the interference wave signal in the second base station,
The second base station transmits the transmission data to the first base station;
The mobile communication system according to claim 13, wherein the receiving unit receives the transmission data from the second base station. The information used for generating the interference replica signal further includes transmission processing information indicating the content of transmission processing when the transmission data is converted into the interference wave signal in the second base station,
The second base station further transmits the transmission processing information to the first base station,
The mobile communication system according to claim 16, wherein the receiving unit further receives the transmission processing information from the second base station. The information used for generating the interference replica signal includes transmission data before being converted into the interference wave signal in the second base station,
The management device transmits the transmission data to the first base station,
The mobile communication system according to claim 13, wherein the reception unit receives the transmission data from the management device. The information used for generating the interference replica signal further includes transmission processing information indicating the content of transmission processing when the transmission data is converted into the interference wave signal in the second base station,
The second base station transmits the transmission processing information to the first base station,
The mobile communication system according to claim 18, wherein the receiving unit receives the transmission processing information from the second base station. The interference wave signal includes a data signal transmitted on a physical downlink shared channel,
The information used for generating the interference replica signal is difference information indicating at least one of an amplitude difference or a phase difference between a reference signal transmitted by the second base station and the data signal,
The second base station transmits the difference information to the first base station;
The mobile communication system according to claim 13, wherein the reception unit receives the difference information from the second base station. The information used for generating the interference replica signal is reception power information indicating reception power for a reference signal received by the user terminal from the second base station,
The user terminal transmits the received power information to the second base station;
The second base station forwards the received power information to the first base station;
The mobile communication system according to claim 13, wherein the reception unit receives the reception power information from the second base station. The information used for generating the interference replica signal is reception power information indicating reception power for a reference signal received by the user terminal from the second base station,
The user terminal transmits the received power information to the first base station,
The mobile communication system according to claim 13, wherein the reception unit receives the reception power information from the user terminal. The interference wave signal includes a data signal transmitted on a physical downlink shared channel,
The information used for generating the interference replica signal is power difference information indicating a power difference between a reference signal transmitted by the second base station and the data signal,
The user terminal transmits the power difference information to the first base station,
The mobile communication system according to claim 13, wherein the receiving unit receives the power difference information from the user terminal. The interference wave signal includes a data signal transmitted on a physical downlink shared channel,
The information used for generating the interference replica signal is power difference information indicating a power difference between a reference signal transmitted by the second base station and the data signal,
The second base station transmits the power difference information to the first base station;
The mobile communication system according to claim 13, wherein the receiving unit receives the power difference information from the second base station. The information used to generate the interference replica signal includes a delay time difference between a delay time from the first base station to the user terminal and a delay time from the second base station to the user terminal. Time difference information indicating
The user terminal transmits the time difference information to the first base station,
The mobile communication system according to claim 13, wherein the receiving unit receives the time difference information from the user terminal. Information used for generating the interference replica signal is channel information indicating channel characteristics between the second base station and the user terminal,
The receiving unit receives the channel information from at least one of the second base station and the user terminal;
The mobile communication system according to claim 13, wherein the control unit generates the interference replica signal based on the channel information received by the receiving unit. The user terminal generates the channel information based on a reference signal received from the second base station, transmits the generated channel information to the first base station,
The mobile communication system according to claim 26, wherein the receiving unit receives the channel information from the user terminal. The user terminal generates the channel information based on a reference signal received from the second base station, transmits the generated channel information to the second base station,
The second base station forwards the channel information from the user terminal to the first base station;
The mobile communication system according to claim 26, wherein the reception unit receives the channel information from the second base station. The first base station transmits cell designation information indicating a cell to be estimated for channel characteristics to the user terminal,
The mobile communication system according to claim 27 or 28, wherein the user terminal generates the channel information by estimating channel characteristics of a cell indicated by the cell designation information. The second base station generates the channel information based on a reference signal received from the user terminal, transmits the generated channel information to the first base station,
The mobile communication system according to claim 26, wherein the reception unit receives the channel information from the second base station. The first base station transmits terminal designation information indicating a user terminal to be a channel characteristic estimation target to the second base station,
The mobile communication system according to claim 30, wherein the second base station generates the channel information by estimating channel characteristics of the user terminal indicated by the terminal designation information. The first base station transmits demodulation information for demodulating the reference signal transmitted by the user terminal to the second base station,
The mobile communication system according to claim 30, wherein the second base station generates the channel information by demodulating the reference signal using the demodulation information. Used in a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal, and a first base station that manages the serving cell A communication control method,
In the first base station,
Generating an interference replica signal corresponding to the interference wave signal;
A superimposing step of superimposing the interference replica signal on the desired wave signal;
Transmitting the desired wave signal on which the interference replica signal is superimposed to the user terminal, and
In the generation step, the interference replica signal is generated so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal. The mobile communication system includes a second base station that manages an adjacent cell that is adjacent to the serving cell and is connected to the other user terminal, and a management device that manages the first base station and the second base station. Further comprising
The communication control method includes:
In the first base station,
Receiving information used for generating the interference replica signal from at least one of the second base station, the management device, and the user terminal;
The communication control method according to claim 33, wherein, in the generation step, the interference replica signal is generated based on the information received in the reception step.   The communication control method according to claim 34, wherein the information used for generating the interference replica signal is channel information indicating a channel characteristic between the second base station and the user terminal. In a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal, the base station manages the serving cell,
A controller that generates an interference replica signal corresponding to the interference wave signal and superimposes the interference replica signal on the desired wave signal;
A transmission unit that transmits the desired wave signal on which the interference replica signal is superimposed to the user terminal,
The base station is characterized in that the control unit generates the interference replica signal so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal. Information used for generating the interference replica signal, another base station that manages an adjacent cell that is adjacent to the serving cell and is connected to the other user terminal, a management device that manages the base station and the other base station, and A receiving unit for receiving from at least one of the user terminals;
The base station according to claim 36, wherein the control unit generates the interference replica signal based on information received by the reception unit.   The base station according to claim 37, wherein the information used for generating the interference replica signal is channel information indicating a channel characteristic between the other base station and the user terminal. In a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal from an adjacent cell adjacent to the serving cell, the base station manages the adjacent cell,
The other base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal,
The base station includes a transmitter that transmits information used to generate the interference replica signal to the other base station.   40. The base station according to claim 39, wherein the information used for generating the interference replica signal is channel information indicating a channel characteristic between the base station and the user terminal. A user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal,
The first base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal,
The user terminal includes a transmission unit that transmits information used to generate the interference replica signal to the first base station.   The information used to generate the interference replica signal is channel information indicating channel characteristics between the second base station and the user terminal that are adjacent to the serving cell and manage an adjacent cell to which the other user terminal is connected. 42. The user terminal according to claim 41, wherein: In a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal, a processor provided in a base station that manages the serving cell,
Generation processing for generating an interference replica signal corresponding to the interference wave signal;
Superimposition processing for superimposing the interference replica signal on the desired wave signal;
Transmitting the desired wave signal on which the interference replica signal is superimposed to the user terminal, and
In the generation process, the interference replica signal is generated so that the interference replica signal received by the user terminal cancels the interference wave signal received by the user terminal. Information used for generating the interference replica signal, another base station that manages an adjacent cell that is adjacent to the serving cell and is connected to the other user terminal, a management device that manages the base station and the other base station, and Further executing a receiving process for receiving from at least one of the user terminals;
44. The processor according to claim 43, wherein in the generation process, the interference replica signal is generated based on the received information.   45. The processor according to claim 44, wherein the information used for generating the interference replica signal is channel information indicating a channel characteristic between the other base station and the user terminal. In a mobile communication system having a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal from an adjacent cell adjacent to the serving cell, a processor provided in a base station that manages the adjacent cell ,
The other base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal,
The processor performs processing for transmitting information used to generate the interference replica signal to the other base station.   The processor according to claim 46, wherein the information used for generating the interference replica signal is channel information indicating a channel characteristic between the base station and the user terminal. A processor provided in a user terminal that receives a desired wave signal from a serving cell and receives an interference wave signal that is a signal to another user terminal,
The first base station that manages the serving cell transmits an interference replica signal corresponding to the interference wave signal superimposed on the desired wave signal,
The processor performs processing for transmitting information used to generate the interference replica signal to the first base station.   The information used to generate the interference replica signal is channel information indicating channel characteristics between the second base station and the user terminal that are adjacent to the serving cell and manage an adjacent cell to which the other user terminal is connected. 49. The processor of claim 48, wherein:

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